N-alkyl and acylphenol coupler solvents for color photography



Unitfid States Pa fit N-ALKYL AND ACYLPHENOL COUPLER SOL- VENTS FOR COLOR PHOTOGRAPHY John R. Thirtle and Arnold Weissberger, Rochester,

N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application August 31, 1955 Serial No. 531,813

7 Claims. (Cl. 96-97) This invention relates to color photography and particularly to novel coupler solvents for color-forming compounds used in coupling development.

Photographic processes in which color-forming compounds or couplers containing phenolic hydroxyl or active methyl groups which are capable of coupling with the oxidation product of a primary aromatic amino developing agent on photographic development to form dyes are now well known. A process of this type in which conplers are incorporated in silver halide emulsion layers by dispersing the couplers in a water-insoluble crystalloidal material such as tricresyl phosphate, which has a high solvent action for the coupler compound and the dye formed from it, was described in Jelley and Vittum U. S. Patent 2,322,027, granted June 15, 1943.

The crystalloidal coupler solvents of the Jelley and Vittum patent have certain undesirable features when used in some photographic systems. For example, certain of the coupler solvents become yellow on aging or cause fading of the dyes formed in the emulsion. Some coupler solvents are unstable toward oxidation or tend to diffuse from the emulsion in which they are incor porated. All of these undesirable properties tend to degrade the final color picture.

We have found a class of coupler solvents which have' improved properties when used to dissolve the couplers and disperse them in photographic emulsion layers.

It is therefore an object of .our invention to provide novel coupler solvents having improved properties. Another object is to provide coupler solvents which do not become discolored or cause fading of the dyes formed in the emulsion layer. A further object is to provide coupler solvents which are less diffusing than those hitherto used and which are more stable toward oxidation. Other objects will appear from the following description of our invention.

These objects are accomplished by dispersing the couplers in photographic emulsions in normal alkylphenol or acylphenol coupler solvents having the following structure:

n= to 17, n+n being 7 to 17 In these compounds there may be two alkyl groups but not more than one of R and R should be an acyl group CO(CH ),,CH

v 2,835,579 Patented May 20, was

' The following compounds may be used according to our invention:

2,4-di-n-amylphenol 2-n-octyl-4-n-amylphenol 2-n-nonyl-4-n-amylphenol 2-methyl-4-n-decylphenol 2-n-decyl-4-methylphenol 2-methyl-4-n-octadecylphenol 2-n-valeryl-4-n-amylphenol Our novel coupler solvents are used in the emulsion in amounts of from 0.05 to 3.0 parts per part of coupler. The quantity selected for use is determined by the solvent power and the effect which the particular coupler solvent produces on the dye absorption characteristics. Our

' couplersolvents possess good permeability to color developers and other processing solutions and do not have deleterious effects on the color of the dye images and stability of the emulsion layers. Also, our coupler solvents do not have a deleterious effect upon residual coupler left in the emulsion layer after processing.

According to the present invention, a sensitive photographic silver halide emulsion such as silver halide in a water-soluble or permeable binder such as gelatin, polyvinyl alcohol or water-soluble synthetic resin is provided,

and the mixture of coupler and coupler solvent is dispersed in discrete particles in the emulsion. and proportions of the coupler and coupler solvent are so chosen that the dispersed particles are liquid under the conditions of coating and processing the emulsion.

The invention, therefore, includes a sensitive silver halide emulsion having a water-soluble or water-permeable binde'r such as gelatin in whichare dispersed particles of liquid consistency composed of coupler and coupler solvent.

the like, the dispersion being stabilized if necessary with emulsifying agents such as those of the well-known higher fatty alcohol sulfate type. The dispersion may be formed by dissolving the coupler and coupler solvent in a solvent of low boiling point such as butyl acetate, dispersing the solution in the gelatin solution or in water, and at a later stage removing the low-boiling solvent by evaporation.

It is sometimes advantageous to employ a mixture of two or more of the novel coupler solvents in the same dispersion in order to obtain the desired combination of properties. Thus, one might use a mixture of one compound having exceptionally good solvent action with another compound added in correct proportions to give the final dispersion the desired refractive index, or to impart the desired absorption characteristics to the dye image.

The following example illustrates the method of incorporating a coupler in the emulsion according to our invention:

One gram of the coupler 2-(2',4-di-tert. amylphenoxy acetamido)-4,6-dichloro-5-methylphenol (Graham U. S. application Serial No. 285,544) was dissolved in 3.0 cc. of 2,4-di-n-amylphenol by heating at C. The warm solution was poured into a mixture of 18 cc. of 10% gelatin solution, 2 cc. of water and 2 cc. of a 10% solution of Alkanol B (sodium tri-is opropyl naphthalene sulfonate). The mixture was then emulsified by passing through a colloid mill and was then mixed with a gelatino-silver halide emulsion and coated. After drying in the usual manner, the emulsion was exposed and developed with Z-amino-S-diethylaminotoluene as the developing agent. After removal of the silver image a cyan dye image of satisfactory properties was obtained.

The following couplers illustrate the variety of compounds containing phenolic hydroxyl or active methylene The nature groups which may be used with the coupler solvents of our invention: I

Other couplers which may be dispersed by dissolving them in the coupler solvents of our invention are disclosed in Weissberger U. S. Patent 2,350,138; Porter et al. U. S. Patent 2,369,489, and Glass et al. U. S. Patents 2,453,661 and 2,455,169.

The following example illustrates the advantages of our coupler solvents in comparison with those of the prior art:

A gelatino-silver halide emulsion was made as described in Jelley and Vittum U. S. Patent 2,322,027, using 6-{a- 4 -[a-(2,4-di-tert-amylphenoxy)butyramidolphenoxy}- acetamido}-2,4-dichloro-3-methylphenol as the coupler and 2,4-di-tert. amylphenol as the coupler solvent. A similar emulsion was made using 2,4-di-n-amylphenol, and the two emulsions were coated, incubated under heat conditions for severaldays, exposed and processed. Tests for speed loss and contrast compared with coatings kept in a The coupler solvents of our invention are prepared by the reaction of cresols or of n-alkylphenols (Sandulesco and Girard, Bull. Soc. .Chim., vol. 47, 1930, page 1300) with aliphatic carboxylic acids in the presence of boron trifluoride. The resulting ketones (acyl-n-alkyl phenols) may be used as suchor reduced by hydrogen and a catalyst to di-n-alkylphenols.

It will be understood that theexamples and modifications described herein are illustrative only and that our invention is to be taken as limited only by the scope of the appended claims.

What we claim is:

1. A light-sensitive photographic emulsion'for producing a colored image by color development, comprising finely-divided liquid particles of a mixture of a coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and a coupler solvent having the structure where R and R are selected from the groups consisting of (CH ),,CH and --CO(CH ),,CH n is from 0 to '17, n+1: being from 7 to 17, and not more than one of R and R being a -CO(CH ),,CH group, said particles being dispersed in a light-sensitive silver halide-organic colloid emulsion.

2. A light-sensitive photographic emulsion for producing a colored image by color development, comprising finelydivided liquid particles of a mixture of a coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and a coupler solvent having the structure where R and R are normal alkyl groups of not more than 18 carbon atoms, the total number of carbon atoms in R and R being from 9 to 19, said particles being dispersed in a light-sensitive silver halide-organic colloid emulsion.

'3. A light-sensitive photographic emulsion for producing acolored image by color development, comprising finely-divided liquid particles of a mixture of a coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and 2,4-

, di-n-amylphenol as a coupler solvent, said particles being dispersed in a light-sensitive gelatino-silver halide emulsion.

4. A light-sensitive photographic emulsion for producing a colored image by color development, comprising finely-divided liquid particles of a mixture of a coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and 2-noctyl-4-n-amylphenol as a coupler solvent, said particles being dispersed in a light-sensitive gelatino-silver halide emulsion.

5. A light-sensitive photographic emulsion for producing a colored image by color development, comprising finely-divided liquid particles of a mixture of a coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and 2-nnonyl-4-n-amylphenol as a coupler solvent, said particles being dispersed in a light-sensitive gelatino-silver halide emulsion.

6. A light-sensitive photographic emulsion for producing a colored image by color development, comprising finely-divided liquid particles of a mixture of a coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and 2- methyl-4-n-decylphenol as a coupler solvent, said particles being dispersed in a light-sensitive gelatino-silver halide emulsion.

7. A light-sensitive photographic emulsion for producing a colored image by color development, comprising finely-divided liquid particles of a mixture of a coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and 2- methyl-4-n-octadecylphenol as a coupler solvent, said particles being dispersed in a light-sensitive gelatino-silver halide emulsion.

References Cited in the file of this patent UNITED STATES PATENTS 2,544,640 Chechak Mar. 13,1951 

